Concept
Poverty of the stimulus (POS) is the controversial argument from linguistics that children are not exposed to rich enough data within their linguistic environments to acquire every feature of their language. This is considered evidence contrary to the empiricist idea that language is learned solely through experience. The claim is that the sentences children hear while learning a language do not contain the information needed to develop a thorough understanding of the grammar of the language. The POS is often used as evidence for universal grammar. This is the idea that all languages conform to the same structural principles, which define the space of possible languages. Both poverty of the stimulus and universal grammar are terms that can be credited to Noam Chomsky, the main proponent of generative grammar. Chomsky coined the term "poverty of the stimulus" in 1980. However, he had argued for the idea since his 1959 review of B.F. Skinner's Verbal Behavior. An argument from the poverty of the stimulus generally takes the following structure: The speech that children are exposed to is consistent with numerous possible grammars. It is possible to define data, D, that would distinguish the target grammar from all other grammars that are consistent with the input. D is missing from speech to children. Children nonetheless acquire the target grammar. Therefore, the right grammatical structure arises due to some (possibly linguistic) property of the child. Chomsky coined the term "poverty of the stimulus" in 1980. This idea is closely related to what Chomsky calls "Plato's Problem". He outlined this philosophical approach in the first chapter of the Knowledge of Language in 1986. Plato's Problem traces back to Meno, a Socratic dialogue. In Meno, Socrates unearths knowledge of geometry concepts from a slave who was never explicitly taught them. Plato's Problem directly parallels the idea of the innateness of language, universal grammar, and more specifically the poverty of the stimulus argument because it reveals that people's knowledge is richer than what they are exposed to.